A depressed beam collector and an RF source comprising a depressed beam collector. The RF source may include, e.g., a multi-beam klystron, a single beam klystron, or other RF sources having an electron gun. The beam collector collects spent electrons from the electron gun and comprises a grounded portion configured to collect a portion of electrons entering the collector and a biased portion configured to collect another portion of the electrons entering the collector and having a depressed energy.